Iridium Recovery: Introduction to Iridium and Extraction Methods for Iridium Containing Waste

Iridium in precious metals has characteristics such as high melting point, high hardness, and good resistance to high-temperature oxidation. This makes it one of the most attractive Platinum group. In Platinum group, the chemical properties of rhodium and rhodium are similar to that of iridium, and its existence in hydrochloric acid medium is very complex. Therefore, the determination of rhodium iridium content and the separation and purification in refining are recognized challenges and have been studied for many years. In the past, Peking University Kunming Institute of Precious Metals and other institutions have done a lot of work in the extraction, separation, and refining of iridium, achieving good results. They have attempted to use it in industrial practice, but have not been able to stably produce qualified products in industrial production.

A method for extracting iridium from iridium containing waste, and the steps of its leaching process include:

1. Dissolve the substance containing iridium in hydrochloric acid;

2. Add nitric acid to the cracking solution for oxidation, then add NH4 Cl for reaction, and filter to obtain iridium platinum mixed ammonium salt;

3. After filtering to obtain a mixture of iridium platinum ammonium salt and adding water to adjust the pH, hydrazine hydrate is added to reduce platinum and precipitate black sponge platinum powder and rhodium and iron impurities. The iridium ammonium salt solution is filtered and separated;

4. Add H 2O 2 to the separated iridium ammonium salt solution, and add residual water from thermal decomposition; Add (NH4) 2 S purification filtration;

5. In the filtered pure chlorine ammonium iridium solution, nitric acid and NH4Cl are sequentially added, and pure (NH4) 2 IrCl6 is precipitated by oxidation to filter the ammonium iridium salt, and (NH4) 2 IrCl6 crystals are refined;

6. Refined (NH4) 2 IrCl 6 crystals were calcined and reduced with hydrogen gas to obtain iridium powder with a purity greater than 99.98%.

This method of extracting iridium from iridium containing waste is characterized by using hydrochloric acid dissolution method with HCl containing iridium waste of 2-6mol/L, with a liquid-solid ratio below 1-6: 1 condition, dissolution for 2-6 hours.

This method of extracting iridium from iridium containing waste is characterized in step (2) by adding the amount of nitric acid in the cracking solution, with the cracking solution consisting of nitric acid=3-6:1 by weight, and adding NH4 Cl with the amount of iridium: NH4 Cl=1:1-4 by weight.

The method for extracting iridium from iridium containing raw materials of the present invention is characterized in step (3) by adding water slurry to achieve an iridium concentration of 10-100 g/L, adjusting the pH to 1.0-2.0, and calculating the amount of added hydrazine hydrate based on the impurity content of rhodium, platinum, and iron. The impurity content is hydrazine hydrate=1:2-5.

This method of extracting iridium from iridium containing waste is characterized in step (4), in which H 2O 2 is added to the separated iridium ammonium salt solution to destroy the residual hydrazine hydrate, and no obvious reaction occurs after the addition of H 2O 2; Adjust the pH to 1.0~2.0, add 0.5%~2% (NH at 75 ℃~80 ℃ temperature 4) for 2 S purification and filtration, and add (NH 4) 2 S to the solution: (NH 4) 2 S=10~15:1 (weight).

This method of extracting iridium from iridium containing waste material is characterized in that in step (5), the amount of nitric acid added is the cracking solution: nitric acid=3-6:1 (weight), and the Adduct of NH3 4 Cl, NH 4 Cl is added to precipitate without forming a reaction end point.

This extraction method extracts iridium from iridium containing materials, characterized by refining (NH4 in step (5)) 2 IrCl6 crystals at temperatures ranging from 750 ℃ to 850 ℃, and reducing them with hydrogen gas at temperatures ranging from 800 to 860 ℃ for 6-8 hours to obtain iridium powder with a purity greater than 99.98%. The advantages of this method are simple process flow, easy operation, reasonable connection between various processes, short cycle, low cost, and stable product quality. Mineral raw materials can be directly used for the separation of Fe, Pt, Pd, Rh, Ir. Alternatively, according to the different Rh content in the materials, all or part of the process flow can be used in the process to fully utilize the process characteristics, reduce operations, and maximize the recovery rate of metals. The material has a wide adaptability and can be a system with complex components. It is a raw material with high content of base metal iron and precious metal platinum rhodium, as well as a large amount of sodium salts and organic residues, or a secondary iridium resource can be recovered. By adopting the process of the present invention, the recovery rate of iridium containing raw materials is greater than 99%, and the product iridium powder is greater than 99.98%. Platinum in slag, liquid, rhodium, etc. can be comprehensively recovered, and the process structure is simple.

The above is only for reference and does not guarantee its accuracy or completeness. The above is an introduction to iridium by Dingfeng Precious Metal Recycling and a detailed answer to the extraction method of iridium containing waste.